1. Field of the Invention
This invention relates to a liquid crystal display panel and a liquid crystal display device which include a pixel area having a display electrode and a reference electrode to modulate light passing through a liquid crystal layer filled between substrates by application of a voltage between the display electrode and the reference electrode.
2. Description of the Related Art
Conventionally, a liquid crystal display device provided with a liquid crystal display panel of the active matrix type which employs an active element such as a thin film transistor has come into use as a display terminal such as an office automation equipment owing to its advantages that it is small in thickness and light in weight and that it displays an image of a high picture quality.
As a liquid crystal display panels of the active matrix type, a display system, such as TV, having a characteristic of such a wide angle of visibility that it can be viewed by a large number of people, that is, a display system of the transverse field type, is known, in which, as described in Japanese Patent Laid-open No. 505247/1993 and Japanese Patent Publication No. 21907/1988, an electric field is formed between a display electrode and a reference electrode, formed on one of opposed substrates, in a direction parallel to the substrates to actuate a liquid crystal filled between the substrates, thereby modulating and displaying the light entering the liquid crystal from a gap between the display electrode and the reference electrode.
However, in the conventional liquid display panel of the horizontal field type disclosed in Japanese Patent Laid-Open No. 505247/1993 or Japanese Patent Publication No. 21907/1988, in addition to an electric field which is produced in a horizontal direction substantially parallel to the substrates, a vertical electric field also is produced in the proximity of side edges of the display electrode and reference electrode. Therefore, the directions of the major axes of molecules of the liquid crystal which originally extend substantially parallel to the substrates are inclined with respect to the substrates. Consequently, leakage of light occurs at or around the side edges of the display electrode and reference electrode, and this deteriorates the contrast. Further, as the major axes of the liquid crystal molecules are inclined, when the electric field disappears, returning of liquid crystal molecules to their original directions is so retarded that a problem of an afterimage phenomenon is produced.